Surimi wash water treatment by chitosan-alginate complexes

small minced fish particles (Park and Morrissey, 2000; Morrissey and others,
2000). The washing is done in 3-4 cycles generating about 5.7 L of SWW for every
kg of raw fish (Huang, 1997). It is estimated that about 50% of total protein are lost
during washing. Surimi wash water (SWW) contains about 0.5-2.3 % total protein
composed mostly of sarcoplasmic proteins with small amounts of the myofibrillar
proteins myosin and actin (Lin and Park, 1996; Park and Morrissey, 2000;
Morrissey and others, 2000). Recovering protein from SWW not only produces
protein that can be potentially used for other purpose but also yields water for
potential reuse in the plant. Removing most of the protein by coagulation will
reduce membrane-fouling problem if the chitosan water treatment is combined with
ultrafiltration.
The mechanism of SWW protein adsorption by chitosan is a combination of
electrostatic interaction between chitosan amino group and anionic groups on the
suspended matter and mechanical entrapment of the proteins in the Chi-Alg
complex network (Savant, 2001). As in cheese whey, Chi-Aig complexes have
shown better protein adsorption than chitosan alone (Savant, 2001; Savant and
Torres, 2000). At 150 mg Chi-Aig complex /L SWW with MR of 0.2 for 24 hours,
the complex adsorbed 78-94% protein in SWW (Savant, 2001), The optimization of
this process in terms of chitosan concentration and reaction time will provide more
economic benefits in treating aqueous food processing streams. An economic
recovery of protein would provide value added benefits to both seafood and
agricultural activities if the solids recovered could be marketed as an animal feed.
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